Common Eelgrass

BotanicalSeagrass

What is it

Common eelgrass (Zostera marina) is a marine flowering plant that grows in coastal seagrass meadows. Extracts appear in a small number of supplements, primarily for their phenolic and polysaccharide content.

How it works

Zostera marina contains phenolic acids (rosmarinic acid, caffeic acid), flavonoids, and sulfated polysaccharides studied in laboratory settings for antioxidant, antimicrobial, and anti-inflammatory activity. Human evidence is limited, so a clinical mechanism cannot be characterized.

Dosage

No standardized intake. Labels are inconsistent on serving size and standardization markers.

When and how to take it

No formal timing guidance. Follow label directions.

1 commercial form

Compare the main delivery options and what they’re best suited for.

Dried plant or extract

Sold as whole-plant or solvent extract in dietary supplements.

Polyphenol absorption is generally low

Safety

Limited published human safety data. The plant is recognized as edible historically (a coastal food in some cultures). Marine plants can accumulate environmental contaminants; choose tested products.

Who should be cautious

Avoid in pregnancy and breastfeeding due to limited data. People with seafood allergies or seagrass exposure sensitivities should use caution.

Interactions

No significant interactions reported in available literature.

Food sources

Eelgrass seeds (historical use)

Amount
variable
%DV
—

Frequently asked questions

What is common eelgrass used for?⌄

Limited supplement use focused on its polyphenol and polysaccharide content; clinical data are sparse.

Is it safe?⌄

Generally considered edible historically. Choose products tested for marine contaminants; clinical safety data are limited.

References

Common Eelgrass on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Common Eelgrass (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.